1. Field of the Invention
This invention concerns a process and a device intended to supply power to an electric motor, particularly a motor driving the arm of an automobile windshield wiper.
2. Description of the Related Art
The state of the art already mentions many powering devices of this type which comprise a motor power control unit connected to a control element under the user's control, comprising windshield arm position sensors and including moreover means for controlling the power to the motor, for example in one direction or the other depending on the position of the arm, in order to sweep a glass surface, for example the windshield or rear window of the vehicle.
These means for controlling the power to the motor comprise for example relays activated by the control unit.
Certain devices likewise comprise means for protecting the electric driving motor in the event the output shaft is blocked, in order to prevent overheating likely to lead to the destruction of the motor.
These means of protection generally consist of a two-blade system arranged inside or outside the motor housing and sensitive to the motor's temperature, in order to interrupt the power supply to the motor when an increase in motor temperature is detected, for example if its output shaft is blocked.
However this structure involves a certain number of disadvantages, especially that of requiring the adjunction of an additional element and its connection to the control unit.
Furthermore, in a certain number of devices of the present state of the art, the operation of the motor power control unit is moreover controlled by a vehicle key contact which, just like the control element, is under the user's control and is in addition connected in series between a source of power supply and the motor powering control unit.
The control element can be a multiple control element, such as for example to control the intermittent or continuous sweeping of the windshield wiper's arm.
In certain devices of the present state of the art, an input terminal for the power to the control unit is connected to the midpoint between the key contact of the vehicle and the control element.
When the user causes the windshield wiper to stop by switching off the control element, the control unit controls the motor power supply so as to have it return the wiper arm to a determined parking position.
On the other hand, if the user operates the vehicle's key contact and opens it while the windshield wiper is running, the power to the motor control unit is interrupted so that the windshield wiper arm stops in the intermediate position.
This is why the device of this invention comprises means making it possible for the wiper arm driving motor control unit to bring the arm back to a parking position after the key contact or the control element is switched off.
In the following, the operation of the power supply device when the vehicle contact is switched on is designated as the contact operating mode. Moreover, the operation of the power supply device after the user has switched off the contact, for example by removing the key, is designated as the contactless operating mode. The purpose of this latter operating mode is to return the wiper arm to its parking position.
The devices of the current state of the art, even when they comprise a contactless operating mode, are not suited to the case when the driving motor is not running.
The invention aims at resolving these problems by proposing a simple and reliable process and a power supply device.